-LRB- CNN -RRB- -- A well-placed pool of water and an air pocket appear to have combined to help a young woman survive for 16 days under the rubble of a collapsed Bangladeshi building .

The woman , who was pulled out Friday from the remains of the garment factory , was found in that pool of water , rescue official Lt. Col. Moazzem Hossain told CNN .

It would have been crucial to her survival , CNN 's Dr. Sanjay Gupta said .

The woman , known only as Reshma , 19 , was able to use an iron rod to get workers ' attention and cry out to them , `` I 'm alive . Please rescue me , '' according to Capt. Ibrahim Islam , a Bangladeshi military official outside the recovery operation .

The rescue was a bright spot against the grim recovery . The death toll from the April 24 collapse is more than 1,000 .

The woman reportedly was in a partially collapsed room and had access to an air pocket , which Gupta said is `` obviously , the most crucial thing . ''

In addition , `` having some access to water must have happened here , '' he noted .

The source of the pool of water was unclear . Water may have trickled to the building 's basement , where Reshma was found , from recent rains and from water sprayed by rescuers . Firefighters had hosed down the area to extinguish a fire that erupted during a failed rescue attempt .

Gupta said the woman likely had some sort of access to food , although people have been known to survive a couple of weeks without it . He said it was `` somewhat surprising '' that Reshma would have been able to call out to rescuers , as `` even that requires a fair amount of energy . ''

Asked how long someone can survive without food or water , Gupta said , `` We keep redefining that a bit . ''

He recalled the case of Evan Muncie , a then-28-year-old man who was pulled alive from a building in Port-au-Prince , Haiti , about four weeks after a January 2010 earthquake that leveled much of the city . It is believed Muncie had some access to food and water , although details remain murky , he said .

Also , Reshma 's youth may have worked in her favor , he said . `` The body can be very good at preserving itself . ''

A body can enter a state known as starvation ketosis , Gupta said , in which it utilizes muscles and other sorts of protein to feed itself .

State-run news agency Bangladesh Sangbad Sangstha -LRB- BSS -RRB- reported Reshma told her rescuers that she survived on dry food and water that was tossed into the rubble in the first days after the collapse .

`` I ate biscuits and water , '' she told rescuers , according to the news agency , `` but the stock dwindled two days ago . ''

Reshma told doctors at a military hospital , where she was taken , that she was wracked by third for the past two days . She spent the entire time in the dark between floors that had collapsed , according to the BSS report .

While Reshma 's outlook is favorable , food will have to be reintroduced slowly , Gupta said , noting that Muncie had lost 30 pounds while buried under the Haitian rubble .

`` My guess is , she 's extremely weak , '' he said .

CNN 's Caitlin Hagan contributed to this report .

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Sanjay Gupta : The pool of water and the air pocket the woman was in were crucial

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Some people can survive without food for weeks , he says

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The body can enter a state known as starvation ketosis